Osteoporotic "hunchback" (thoracic hyperkyphosis)

As you age, your bones lose some of their strength due to osteoporosis. Constant excessive pressure on the front of your vertebra over time can lead to the formation of wedge shaped vertebrae resulting in “hunchback” or “dowagers hump”. 

Bone softening combined with excess pressure can lead to compression fractures and collapse of the front of your vertebra, which further increases the hunching. These compression fractures are often painless in themselves but may place extra loads on your mid-back, neck, lower back, ribs, lungs, heart, and digestive system.

The mid-back spinal muscles that support your upright posture often become fibrotic, stiff and weak making them less able to work against the forces of gravity and help maintain your spine in a hunched position. Frequently, there are a number of unnecessary behaviors or habits that exacerbate the condition.